The present invention relates generally to the correction of deficiencies in mandibular growth. More specifically, the present invention relates to a device for mandibular distraction osteogenesis the (lengthening of the lower jaw by stretching) for correcting deficiencies in mandibular length.
Deficiencies in mandibular growth which lead to characteristic protrusions of the maxillary teeth and deficiencies of the chin are quite common in American and Northern European populations. Data from recent large scale U.S. Public Health Service surveys of the occlusion of children and youth ages 6 through 10 indicate that about 20 percent of the U.S. population has mandibular deficiency, and about 5 percent of the total U.S. population has skeletal mandibular deficiency (deficiency in the growth of the lower jaw) so severe that the only way to correct such deficiency is to perform a total mandibular (lower jaw) resection (osteotomy) and to advance the lower jaw to a more favorable forward position.
A total mandibular osteotomy, or a sagittal split osteotomy, is a major surgical procedure that can have many complications. In this procedure, as illustrated in FIG. 1, a human mandible is split at opposite points on the mandible. The forward part of the mandible is then brought apart from the rearward part and stabilized with either: (1) screws at point S as labeled in the figure (the forward part F is indicated in FIG. 1 by the arrows A as having been moved; this procedure is used less commonly now than in previous years due to the inherent difficulty in positioning of three loose parts of the mandible correctly during the surgery) or (2) splinting of the broken lower jaw to a prefabricated interocclusal splint which is secured to the upper jaw and allowing it to heal for approximately 2 months (during which the patient cannot open his/her mouth, cannot communicate or function and is fed through a straw).
This procedure cuts the bone marrow, and thus could be detrimental to the inner nerves and blood vessels of the mandible.
In addition, a total mandibular osteotomy can involve the complications of bleeding, obstruction of the airway, possible infection, neurological problems such as possible paralysis of the inferior alveolar nerve and loss of sensation to the lip, failure of intermaxillary fixation (stabilization of the mandible after surgery), relapse-movement of the lower jaw in the direction from which it was advanced, and possible displacement of the temporo-mandibular jaw joints during the surgery.
Needless to say, such surgery requires a hospital stay, is very expensive and many patients are reluctant to agree to this. Further, total treatment time is on the order of 30 months.
The other 15 percent of mandibular deficiencies are less severe, and if they are caught early, during the pubertal growth stage, are amenable to conventional orthodontics (braces) or a combination of orthodontics and functional appliance treatment. However, functional appliances are of most benefit to a patient when the patient is undergoing body and jaw growth, and cannot benefit adult (non-growing) patients.
One other prior art surgical technique bears mention. A process of lengthening human long bones (limbs, arms, etc.) by distraction osteogenesis has been utilized for the past 40 years. This process was designed by a Russian surgeon, Dr. Gavriel A. Ilizarov. The principles of the method of Dr. Ilizarov are presented in an article based on a speech delivered by Dr. Ilizarov on Oct. 30, 1987 at the annual Scientific Program of the Alumni Association and material presented by Dr. Ilizarov at a three day international conference on the Ilizarov techniques for the management of difficult skeletal problems. His technique is being widely used by orthopedic surgeons throughout the United States and the world.